Compile for running on simulator

How do I compile the FastPDFKit embedded framework so I can add it to a project and run the project on a simulator? I have added x86_64 to the Architectures and Valid Architectures Debug Build Settings, and set the scheme to use the Debug build configuration for Run. However, when I do a Build for Running, I get Unsupported architecture errors.

For reference, a framework cannot be fat - containing both simulator and device - unless is manipulated with lipo. If you embed the framework manually, you have to compile it each time you change target (simulator or device). It is far easier to add the FPK project in the app workspace and add the framework as an Embedded binary to the app target. Xcode will automatically manage the architecture.